Incidence and determinants of spontaneous normalization of subclinical hypothyroidism in older adults
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CONTEXT: With age, the prevalence of subclinical hypothyroidism rises. However, incidence and determinants of spontaneous normalization remain largely unknown.
OBJECTIVE: To investigate incidence and determinants of spontaneous normalization of thyroid-stimulating hormone (TSH) levels in older adults with subclinical hypothyroidism.
DESIGN: Pooled data were used from the (i) pre-trial population, and (ii) in-trial placebo group from two randomized, double-blind, placebo-controlled trials (TRUST and IEMO thyroid 80-plus thyroid trial).
SETTING: Community-dwelling 65 + adults with subclinical hypothyroidism from the Netherlands, Switzerland, Ireland, and the United Kingdom.
PARTICIPANTS: The pre-trial population (N = 2335) consisted of older adults with biochemical subclinical hypothyroidism, defined as ≥1 elevated TSH measurement (≥4.60 mIU/L) and a free thyroxine (fT4) within the laboratory-specific reference range. Individuals with persistent subclinical hypothyroidism, defined as ≥2 elevated TSH measurements ≥3 months apart, were randomized to levothyroxine/placebo, of which the in-trial placebo group (N = 361) was included.
MAIN OUTCOME MEASURES: Incidence of spontaneous normalization of TSH levels and associations between participant characteristics and normalization.
RESULTS: In the pre-trial phase, TSH levels normalized in 60.8% of participants in a median follow-up of one year. In the in-trial phase, levels normalized in 39.9% of participants after one year follow-up. Younger age, female sex, lower initial TSH level, higher initial fT4 level, absence of thyroid peroxidase antibodies, and a follow-up measurement in summer were independent determinants for normalization.
CONCLUSIONS: Since TSH levels spontaneously normalized in a large proportion of older adults with subclinical hypothyroidism (also after confirmation by repeat measurement), a third measurement may be recommended before considering treatment.
Original language | English |
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Journal | The Journal of clinical endocrinology and metabolism |
Volume | 109 |
Issue number | 3 |
Pages (from-to) | e1167–e1174 |
Number of pages | 8 |
ISSN | 0021-972X |
DOIs | |
Publication status | Published - 2024 |
Bibliographical note
© The Author(s) 2023. Published by Oxford University Press on behalf of the Endocrine Society.
ID: 374396751